The present invention relates, in general, to semiconductor devices, and more particularly, to a novel silicon carbide transistor.
Silicon carbide transistors typically are formed on a silicon carbide substrate. Often, the source and drain areas are a series of alternating stripes that are formed into a top surface of a thick bulk single crystal silicon carbide substrate. A portion of such a prior art structure is shown in FIG. 1 wherein a transistor 100 is formed on a thick, typically greater than about three hundred microns, bulk single crystal silicon carbide substrate 101. Transistor 100 has a source 102 that is formed as a long rectangular stripe on the top surface of substrate 101. A drain 103 is also formed as a rectangular stripe on the top surface of substrate 101. A metal gate 104 is formed on the top surface between source 102 and drain 103. A drain electrode 107 is formed on top of drain 103 and is used to interconnect drain 103 to other drain areas on transistor 100. In order to connect source 102 to other source areas on transistor 100, a source electrode 106 is typically formed as an air-bridge extending from source 102 up into the air across gate 104 and drain electrode 107 to an adjacent source area. Such air-bridges are well known to those skilled in the art. Some disadvantages of such air-bridge structures are that they are difficult and expensive to fabricate, and such structures are unreliable. Additionally, such air-bridges result in excess source impedance thereby effecting the performance of transistor 100.
Accordingly, it is desirable to have a silicon carbide transistor that does not utilize air-bridges, that reduces manufacturing cost, and that minimizes source impedance of the transistor.